Utility of a nitric oxide electrode for monitoring the administration of nitric oxide in biologic systems

Von Hippel-Lindau (VHL) disease is an inherited autosomal dominant neoplastic disorder causing central nervous system haemangioblastomas. The VHL gene (3p25-3p26) is known to be a tumour suppressor gene, with its inactivation being responsible for a predisposition to tumour development. As far as we know, the present report of VHL disease manifestation in identical twins is unique. Genetic inquiry into the family background did not reveal this disease among their progenitors. For presymptomatic diagnosis of 17 presently unaffected family members, constitutional DNA of the twins was screened for VHL germline mutations, using loss of heterozygosity studies and exon-specific DNA sequencing. To determine the influence of somatic mutations of the VHL gene in tumourigenesis, DNA of five surgically removed intracerebral haemangioblastomas of the identical twins was analyzed in comparison with their constitutional DNA by DNA sequencing of the complete VHL coding region. However, no allelic losses were found for the VHL gene or for various other tumour suppressor genes (p53, BRCA1, BRCA2, DCC, and MCC). Furthermore, no mutations were found in the constitutional DNA of either twin sister or in the DNA of all five tumour lesions. Based on our observations, we conclude that in certain VHL families, presymptomatic molecular diagnosis of the disease is not feasible and requires close clinical surveillance of all individuals at risk.     

Well reservoir model identification using translation and scale invariant higher order networks

This paper describes the use of higher order neural networks to identify well reservoir response models from test data. Well reservoir response models are characterised by a family of parametrically related curves. Neural networks can in principle offer an interesting approach to the identification problem as data are often uncertain and incomplete. However, it turns out that the well reservoir model, viewed as a curve in two dimensions, is invariant with respect to translation and changes of scale of the axes. This poses severe problems for a standard backpropagation network using the two-dimensional plot as an input retina. This difficulty can be overcome by using a higher order network in which the output is forced to be invariant with respect to the required transformations of the retina. In this way, the potentially huge number of weights is significantly reduced using the invariance condition as a constraint which acts so as to divide the weights into equivalence classes within which they are equal. The resulting network can then be trained using standard techniques. We contrast this network approach with classical methods of model identification.     

Kinetics of the methanogenic fermentation of acetate

The kinetics of methanogenesis from a stirred batch-fed calcium acetate enrichment culture have been studied. A detailed kinetic analysis of the culture allowed four distinct phases to be distinguished. Phase 1 was a period of very rapid increase (from low initial values) in the rate of methanogenesis upon addition of acetate, and was not thought to be associated with cell growth. In Phase 2 the rate of methanogenesis increased exponentially with time reflecting exponential growth. Phase 3 was characterised by an approximately constant rate of methane production, and is discussed in relation to the uncoupling of growth and methanogenesis. Phase 4 is a period of rapid decline associated with depletion of acetate. The apparent size of the population of the acetate-utilising methanogenic bacteria subsequently declined, with a specific decay constant of 0.4 ± 0.1 d^?1. The significance of these phases, in particular 2 and 3, for industrial anaerobic digestion is discussed.     

Low-noise implanted-base microwave transistors

An improved small-signal bipolar microwave transistor utilizing ion-implantation has been developed. The structure comprises oxide isolation, arsenic-doped emitters and an ion-implanted base region. A noise figure of 3·9 dB at 8 GHz has been achieved. The variation of the device parameters with the implanted dose has been investigated and the results are interpreted in terms of a simplified model. Implanted emitters and diffused emitters have been evaluated and found to give similar results.     

Waiting list dropouts in a university counseling center.

Surveyed 59 clients at a university counseling center who had been placed on a waiting list and subsequently decided not to renew their request for counseling. Ss were asked why they did not renew their request and whether they were still interested in counseling. Responses were analyzed in terms of type of problem, time on the waiting list, and degree of urgency. Most Ss did not report negative reactions or effects from their placement on the waiting list, although Ss in the highest urgency category tended to report that the wait was too long. 30 Ss stated that the intake interview was enough or that the problem had been resolved, while 23 were still interested in counseling. It is suggested that (1) high-urgency clients should be given priority at university counseling centers, (2) directive crisis-intervention approaches can be used to resolve issues at intake sessions, (3) assessment should identify clients whose motivation for counseling is related to developmental issues that need to be dealt with immediately, and (4) alternative treatments such as groups or workshops should be made available to waiting-list clients. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vocal fold scarring: current concepts and management

Scarring of the vocal folds can occur as the result of blunt laryngeal trauma or, more commonly, as the result of surgical, iatrogenic injury after excision or removal of vocal fold lesions. The scarring results in replacement of healthy tissue by fibrous tissue and can irrevocably alter vocal fold function and lead to a decreased or absent vocal fold mucosal wave. The assessment and treatment of persistent dysphonia in patients with vocal fold scarring presents both diagnostic and therapeutic challenges to the voice treatment team. The common causes of vocal fold scarring are described, and prevention of vocal fold injury during removal of vocal fold lesions is stressed. The anatomic and histologic basis for the subsequent alterations in voice production and contemporary modalities for clinical and objective assessment will be discussed. Treatment options will be reviewed, including nonsurgical treatment and voice therapy, collagen injection, fat augmentation, endoscopic laryngoplasty, and Silastic medialization.     

破碎空间系统中的步行人流和社区形态：马萨诸塞州波士顿实例

此论文探讨了在破碎的、可理解性低的空间系统中空间布局和网络组构对步行人流的影响,同时也评价了社区形态在形成不同尺度之间的关系中所扮演的角色,而这被认为是有助于产生城市生活的感觉和活力。在传统空间句法研究中“,可理解性”被定义为局部可达性(即连通性)与整体位置(即整体整合度)的相关度。传统空间句法理论认为在这些情况下空间和运动的相互关联度极低,从而将导致更低的可预测性,或者可称其为明显的随机运动形态。此论文建议对局部区域形态的仔细研究和重叠社区的边界分析,可以被用来理清复杂和难以识别的环境,以及它对步行运动的真实影响。通过多元回归分析和一种称为“相关性等高映射”的新技术对马萨诸塞州波士顿市的实例研究来探讨这个假设。“相关性等高映射”技术可以显示出复杂空间系统中的不同可预测性的边界,以及局部区域与其周边环境间新的内在联系。波士顿的例子(相关度r2在0.65～0.94之间)说明空间在对步行人流的影响中扮演着重要的角色,但是空间与不同的区域和使用者之间的关系并不是完全相同的。为了完全了解大规模城市建设对破碎的网络结构的干扰作用,就有必要认识局部区域形态和重叠边缘地带的影响。此研究以刘易斯·芒福德、简·雅各布斯、凯文·林奇和比尔·希利尔的社区形态和都市生活概论为基础。